Many outdoor lighting systems are configured to be activated from dusk until dawn. One example of such a system is a solar powered street light. As the sun sets, the amount of current or voltage of the electrical energy generated by the photovoltaic panel decreases. A system controller can detect this decrease in current or voltage. Once the amount of current or voltage falls below a predetermined threshold, the controller can turn on the street light. The light can remain on until the current or voltage of the electrical energy generated by the photovoltaic panel again exceeds a predetermined threshold. For instance, as the sun rises and its light energy impinges on the photovoltaic panel, the amount of current or voltage generated by the photovoltaic panel can increase. When the amount of current or voltage exceeds the predetermined threshold, the system controller can turn off the street light.
However, the presence of nearby manmade light sources can interfere with the desired operation of the system. For example, light energy from the street light itself may impinge on the photovoltaic panel, which, alone or in combination with light energy from other sources, may be able to generate sufficient current or voltage to exceed the predetermined threshold. In such case, the controller will turn off the street light. With the light off, the amount of current or voltage of the electrical energy generated by the photovoltaic panel will decrease, eventually to an amount below the predetermined threshold, which will cause the controller to turn on the streetlight again. Such on-off cycling of the light may repeat throughout the entire night.
In addition, light energy from other nearby light sources, like other street lights, building lighting, sign lighting, and/or stadium lights, may also impinge upon the photovoltaic panel. These nearby light sources can contribute to the repeated on-off cycling of the street light or may keep the street light off for long periods of time during the night, if not for the entire night. Without a way to distinguish between light from natural sources and light from itself or from other manmade sources, the system may not work in the intended manner, thereby frustrating the very purpose of the system.
Thus, there is a need for a system that can minimize such concerns.